United States Air Force Plant 42 is a federally owned military aerospace facility in Palmdale, California where aerospace contractors share a common runway complex, and either lease building space from the Air Force, or own their own building outright (commonly referred to as GOCO, or Government Owned Contractor Operated). There are eight separate production sites specially suited for advanced technology and/or "black" program projects. Currently the most well known contractors at Plant 42 are Boeing, Lockheed Martin, and Northrop Grumman.
Located in the southern Antelope Valley, Plant 42 is strategically located near Los Angeles area defense and aerospace contractor companies, as well as Edwards Air Force Base's high-speed test corridors used under the direction of the base's Air Force Flight Test Center (AFFTC). It is 65 miles (105 km) from the LA Civic Center and 37 miles (60 km) from Edwards' flightline.
* B-2 Spirit
* F-22 Raptor
* F-35 Joint Strike Fighter (JSF)
* F-117A Nighthawk
* Global Hawk
* Each of the Space Shuttles
* Modernization of the Space Shuttle Columbia's cockpit area
* Lockheed L-1011 Tristar passenger jet
* B-1 Lancer Bomber
* SR-71 Blackbird
The property now called Plant 42 was first activated as an emergency air landing strip in 1940 prior to the entry of the United States in World War II. It also provided B-25 training to military aviators during the war. Declared surplus by the federal government in 1946, it became a commercial airport for Los Angeles County. The outbreak of the Korean War in 1950 caused the Air Force to reactivate the property for use in final assembly and flight testing of military jet aircraft.
Both the U. S. Air Force and its aircraft contractors needed a location away from major population centers - due to sonic booms, other noises and security concerns - but close enough to the major centers of aircraft design and production, while having excellent flying weather the year around. The land which became Plant 42 fit the bill perfectly from the perspectives of all the concerned interests in military aircraft and national defense. Consequently, the Air Force agreed to purchase the land from Los Angeles County in 1951. Lockheed put together a master plan for the property per its Air Force contract, and after the approval of this master plan in 1953, the County transferred ownership of the land to the Federal Government in 1954. Since then Lockheed, looked upon with favor by the Air Force at this time, established its permanent presence at Plant 42. Its first step in doing so was to sign a lease in 1956 for 237 acres (1 km²) for use in its Air Force support programs of manufacturing aircraft and flight testing.